Add `proxy_ca_certificate_file` output to `start-proxy` action #4693

Job	Run time
Ruby analysis (ubuntu-latest, linked)	45s
Ruby analysis (macos-latest, nightly-latest)	50s
Ruby analysis (macos-latest, linked)	48s
Ruby analysis (ubuntu-latest, nightly-latest)	46s
Ruby analysis (macos-latest, default)	46s
Ruby analysis (ubuntu-latest, default)	44s
	4m 39s

Provide feedback